Steam engine inlet valve mechanism



9,1968 H. v. STURTEVANT 3,397,619

STEAM ENGINE INLET VALVE MECHANISM Filed Dec. 19, 1956 I 2 Sheets-Sheetil INVENTOR.

HAROLD V. STU RTEVANT ATTORNEY Aug. 20, 1968 H. v. STURTEVANT STEAM ENGINE INLET VALVE MECHANISM 2,Sheets-Sheet 2 Filed Dec. 19, 1966 INVENTOR.

HAROLD V. STURTEVANT BY wwqaf lmdgk ATTORNEY United States Patent 3,397,619 STEAM ENGINE INLET VALVE MECHANISM Harold V. Sturtevant, 173 Norwood Ave., North Plainfield, NJ. 07060 Filed Dec. 19, 1966, Ser. No. 602,748 6 Claims. (Cl. 91175) ABSTRACT OF THE DISCLOSURE A steam engine having a plate inlet valve opened by the piston and held open by an electromagnet for governor cut-off control, a thrust bearing movable axially of the main shaft mounted on a screw to vary clearance at top dead center, and a small area starting valve opened by an electromagnet against steam pressure.

Background This invention relates to steam engines, and more particularly to the reciprocating type having a cylinder and a piston slidable therein, with inlet and exhaust valves for passing steam into and out of the cylinder in timed relation to the strokes of the piston therein.

Prior art Kelly 2,649,078 and Schmiedeskamp 2,671,434 have no electromagnet to hold inlet valve open for cut-off control.

Ray 2,604,079 has no piston operated valve opening, hence electromagnet requires much electric power to open inlet valve against steam pressure.

Summary Steam engines have been supplanted largely because of weight and space requirements, low efficiency, slow speed, and complicated valve gear. However, steam turbines in smaller sizes are not efiicient at low speeds and light loads, and internal combustion engines are objectionable because of noise, air pollution, and high specific fuel consumption.

The main objects of the present invention are therefore to reduce the Weight and space requirements, increase the efficiency and speed, and simplify the valve operation of the steam engine, and to provide positive means for starting the engine.

A specific object in order to eliminate complicated valve gear, is to provide an inlet plate valve opened by the engine piston, and preferably held open by an electromagnet which gives cut-off control through a rotatable contact on the engine shaft, also to provide a supplementary valve for admitting steam independently of the main valve for starting purposes.

Another object is to direct the incoming steam toward close contact with the hot cylinder wall and to keep it away from the relatively cooler exhaust valve and piston head, thus reducing cylinder condensation and increasing the expansive power of the steam by heat pick up from the cylinder wall.

In the drawings:

FIGURE 1 is an axial section through a two cylinder wobble plate steam engine according to the preferred embodiment of the present invention;

FIGURE 2 is an isometric diagram of the governor and control mechanisms for the engine shown in FIG- URE 1; and

FIGURE 3 is an enlarged portion of FIGURE 1, showing the details of the main valve and the starting valve.

FIGURE 4 is an end view of the starting valve.

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The steam engine shown in the drawing comprises a two cylinder uniflow engine operating on the wobble plate principle, so as to get the most power in the smallest volume and weight. Each cylinder delivers a power stroke at every revolution of the shaft.

In the form shown, the steam engine comprises a frame 10 with a main shaft 12 journaled therein, and a cylinder 14 having a steam chest 15 with a steam inlet 16 and a cylinder head 17 provided with a central inlet port 18. An inlet plate valve 20 concentric with the port 18, is mounted in the steam chest 15 and normally held closed by a coil compression spring 22, and also by steam pressure. Within the steam chest 15, concentric with the valve 20, is an electromagnet 26, which is energized by an adjustable rotatable contactor mounted on the engine shaft 12 and controlled by a governor.

Slidably mounted in the cylinder 14 is a piston 28 which is adapted to exert thrust upon the inlet plate valve 20 by valve opening parts hereinafter described, to open the plate valve 20 near the top dead center of the piston stroke. In the form shown, the piston is a double ended casting serving as both a piston and a crosshead. The piston head uncovers exhaust ports 30 in the cylinder wall, to release exhaust steam.

Mounted in the inlet port 18 is an admission rotator 38 of spiral form which gives the incoming steam a whirling motion as if it were tangentially admitted. This throws the steam outward to the hot cylinder wall, and keeps the steam in longer and more intimate contact with the hot cylinder wall throughout the expansion or power stroke.

Integral with the rotator 38 is a conical admission diverter 40 which directs the steam radially to further improve the contact between the steam and the hot cylinder wall. The rotator 38 and diverter 40 form a solid thrust block of inlet valve opening parts. When the piston 28 approaches top dead center it opens the inlet valve 20.

The connecting rod end of the piston 28 forms a crosshead 46 journalling a connecting rod 48 which drives a wobble plate 50 and thrust block 52 keyed to the main shaft 12. This shaft is journalled in a stationary frame bearing 54 having screw threads meshing with those of a thrust bearing 56. Limited rotation of this thrust bearing is provided by a hydraulic cylinder 58.

The purpose of this arrangement is to control the position at top dead center of the reciprocating pistons so that at very light loads, when too much steam will otherwise be admitted because of inlet valve opening prior to top dead center, only enough steam will now be admitted to maintain constant speed. Rotation of thrust bearing 56 in a direction to reduce speed, will pull back all moving parts including the pistons, away from the cylinder head, and from inlet valve opening parts 38 and 40, and when this motion is carried to the extreme, the inlet valve will not open at all, and the engine will stop. This arrangement provides cut-off control of speed down to zero load without need for throttling steam flow, which is wasteful.

The electromagnet 26 is not intended to open the inlet valve by magnetic force, since the considerable force required to open the valve against steam pressure is more easily and less expensively provided by the piston. The magnet 26 is intended only to hold the valve open long enough during the power stroke to obtain the desired cutolf. The above provisions for opening and closing the inlet valve make possible the complete elimination of the usual valve gear with the attendant eccentrics, connecting rods, push rods, stuffing boxes, et cetera.

Adjustable cut-01f is thereby established for maintaining constant speed from zero to full load, without throttling steam pressure.

As shown in FIGURE 2, a commutator 60 is mounted on and insulated from the main shaft 12. This commutator is contacted by one contact or rotatable brush 62, and one fixed bnish 64. The fixed brush 64, which is immovably mounted so as to make contact with commutator segment 60 only after corresponding piston has passed top dead center, will therefore complete the electric circut through segment 60, rotatable brush 62, battery, main switch 86, solenoids 26 and 85, and back to brush 64, only after corresponding crank has passed top dead center. Commutator segment 60 extends around 180 degrees of crankshaft rotation. In the case of a two cylinder engine with cranks 180 degrees apart, the second cylinder, having its own set of brushes 64 and 62, and commutator segment 60, would have its brush 64 in contact with its segment 60, thus completing the circuit for its starting valve, when the first cylinder has its brush 64 out of contact with its segment 60, as shown in FIG. 2. This means that an engine having only two cylinders would always have either one or the other with its circuits closed for energization of its solenoids 26 and 85, upon closing of main switch 86.

During the period of starting, engine speed would be very low, and consequently the governor 72 would be calling for more steam by increasing the cut-oif to maximum. Governor 72 would automatically have moved brush 62 the maximum amount in the direction of engine rotation by means of lever 68, rod 66, so as to maintain the flow of electric current to solenoids 26 and 85 throughout the entire power stroke. This causes starting valve 84 to admit steam to its corresponding cylinder, no matter where the piston in that cylinder may be at time of starting.

For reverse direction of rotation, each cylinder has another set of brushes and commutator (not shown), mounted 180 degrees from the ahead set shown in FIG. 2. A single pole, double throw switch (not shown) serves to conduct the current either to the ahead brush 64 or the reverse brush 64 (not shown) for control of direction of rotation. If there are more than two cylinders, then there will be as many more power impulses per revolution for starting as well as for normal running, as there are additional cylinders.

The starting valve 84 can be mounted co-axially with main valve 20, as shown in FIG. 3, and both attracted by solenoid 26, or starting valve 84 can be mounted separately as shown in FIG. 2 and operated by solenoid 85. In the latter case, an oil pressure operated switch 87 can be used to disconnect solenoid 85 after engine starts and system oil pressure builds up, in order not to continually operate the starting equipment after there is no need for it.

Commutator section 60 extends around the main shaft 12 approximately 180 degrees starting in the plane of the top dead center, and in that half rotation following top dead center. The rotatable brush 62 is connected by rod 66 to lever 68 pivoted at 70. This lever is moved either by manual control or by governor 72 to regulate the percent of cut-oil, and thus control the speed or power or both.

Either governor 72 or manual control lever 68 also rotates thrust bearing 56. Lever 68 receives a rod 74 between coil springs 76 and 78 thereon. The rod 74 is connected to crank pin 80 on the thrust bearing 56. On starting, the spring 76 is compressed when the thrust bearing is rotated in a direction to lift or open the inlet valve 20.

Since it is desirable to attain full inlet valve travel as soon as possible after starting, these linkages are so proportioned that thrust bearing 56 reaches its maximum power operating position before rotatable contactor 62 has reached its maximum cut-ofi" position. This limits the influence of rotatable thrust bearing on speed or power control to light loads or low speeds, and permits the magnetic cut-off control to handle most of the regulating.

The purpose of the spring 78 is for return of the thrust bearing 56 to zero cut-off point. Rotation of the thrust bearing 56 is limited by stops 82 to that range of rotation which takes inlet valve lift from zero to maximum.

The engine is provided with a small starting valve 84, because without this, if engine pistons are stationary and both out of contact with inlet valves, then there is no motion of the pistons to open the inlet valves and the engine will not start. Closing of main switch 86 will not lift the main valve 20, since solenoid 26 is not strong enough to open inlet valve 20 against steam pressure. The smaller starting valve 84 will open however, by solenoid 26, since the opposing force of steam acting on starting port is less than the upward pull of the solenoid 26 on starting valve 84, and will admit steam to whichever piston is past dead center. The other piston will then move toward top dead center, and will open its main inlet valve. The engine will then operate.

FIGURE 3 shows the preferred embodiment, in which the starting valve 84 has a stem 88 which extends into the solenoid 26. The starting valve 84 also has a depending axial boss 89 of small diameter covering a starting port 90 of still smaller diameter in the center of the main inlet valve 20. The boss '89 reduces the area of the starting valve subject to steam pressure. The boss 89 also forms a gap 92 to space the greater part of the starting valve from the main valve, so that the electromagnet will exert the greater part of its pull on the starter valve but will have enough pull left to retain the main valve 20 once it has been pushed up against magnet 26 by the piston 28. On starting, the main valve will stay closed because of greater steam pressure on greater area until pushed open by the piston. The starting valve will be opened by the electromagnet 26, on closure of main switch 86 and after the main valve 20 is opened by the piston, it will be held in open position by solenoid 26 under governor or manual control. The small port 90 remains closed during normal operation since the main valve 20 is operated by the piston ahead of top dead center and will carry starting valve 84 along with it in the closed position.

What is claimed is:

1. Steam engine having a frame with a main shaft journaled therein, said engine being of the reciprocating type having a cylinder and a piston slidable therein with inlet and exhaust valves for passing steam into and out of the cylinder in timed relation to the strokes of the piston therein, and means actuated by said piston for driving said main shaft, said cylinder having a head with an inlet port therein, a spring pressed inlet valve in said head closing said inlet port, inlet valve opening means extending through said inlet port into said cylinder, said piston in said cylinder engaging said valve opening means to open said valve, an electromagnet mounted in said cylinder head to hold said inlet valve open after it has been opened by the piston, and a rotatable contact mounted on said main shaft to energize and deenergize said magnet for cut-oif control, said cylinder 'being provided with a supplementary steam valve for starting purposes for admitting steam to the cylinder independently of the main inlet valve.

2. Steam engine as claimed in claim 1, in which a conical steam admission diverter is mounted in said inlet port to keep the steam away from the piston head and keep it close to the cylinder wall.

3. Steam engine as claimed in claim 1, in which a helical steam admission rotator is mounted in said inlet port to give the steam a whirling motion.

4. Steam engine as claimed in claim 1, in which said starting valve is separate from and smaller than said inlet plate valve, and operated by the same electromagnet as the main valve.

5. Steam engine as claimed in claim 1, in which said engine comprises at least a pair of said cylinders in par allel relation and equally angularly spaced about said References Cited main shaft, and said driving means comprises connecting UNITED STATES PATENTS rods for sa1d pistons of sa1d cylinders, and a wobble plate driven by said connecting rods for rotating said 9 7 3/ 9 H d shaft. 5 1,210,649 1/1917 Holley et a1 91-175 '6. Steam engine as claimed in claim 4, in which the 2,957,462 10/1960 Clark 91175 circuit of the electromagnet is opened by a switch re- 3,216,329 11/1965 Peterson 91-341 sponsive to oil pressure generated by starting of the engine. PAUL E. MASLOUSKY, Primary Examiner. 

